Pocket combination for extension for speed and load range of awm supercharger



Sept. 14, 1965 J. WALEFFE ETAL 3,206,107

POCKET COMBINATION FOR EXTENSION FOR SPEED AND LOAD RANGE OF AWM SUPERCHARGER Original Filed Aug. 22, 1961 2 Sheets-Sheet 1 6 HP INLET PORTC HP oum'r FOR 7' 0 Z EA a 6% Z HP OUTLET LP/NLET PORT 5 ZPOUTLIT 56 FOR? A INVENTORS .1035 WALL'FFE ERNST JENNY KURT MULLER Sept. 14, 1965 .1. WALEFFE ETAL 3,206,107

POCKET COMBINATION FOR EXTENSION FOR SPEED AND LQAD RANGE OF AWM SUPERGHARGER Original Filed Aug. 22, 1961 2 Sheets-Sheet 2 HP INLET PORT C 4 Q 5 5 M HP INLET F/G. 4

PORT a HPOUTLH PORTD 58 EA a 1 b E 2 F/GI 5 LP INLET L LP OUTLET PORTA p 3 FIG 5 25 5 HP INLET a 1 PoPrc HP OUTLET PaPr o i 59 LP OUTLET PORT 4 LP INLET PORT a INVENTORS .1085 WALEFFE ERA/$7 JEN/V) KURT MULLER BY flrm'azF/m; 5705/1, 55! ,5 Paris/v ATTORNEYS United States Patent POCKET COMBINATION FOR EXTENSION FOR SPEED AND LOAD RANGE OF AWM SUPER- CHARGER Jose Waleife and Ernst Jenny, Baden, Switzerland, and

Kurt Muller, Philadelphia, Pa., assignors to Brown- Boveri & Company, Ltd, Baden, Switzerland, a corporation of Switzerland Original application Aug. 22, 1961, Ser. No. 133,104, now Patent No. 3,120,920, dated Feb. 11, 1964. Divided and this application Mar. 5, 1963, Ser. No. 268,850

2 Claims. (Cl. 23069) This application is a division of US. application S.N. 133,104 filed August 22, 1961 and now issued as US. Patent 3,120,920 on February 11, 1964.

Our invention relates to pressure exchangers and, more particularly, is directed to a novel construction for pressure exchangers which are directly driven by the unit being supercharged by the pressure exchanger.

Pressure exchangers are well known in the art and the general arrangement to which our invention is directed is illustrated in several prior art patents, such as: US. Patent 2,853,987 issued September 30, 1958 to M. Berchtold et al., entitled Diesel Engine Supercharging by The Aero-Dynamic Wave Machine; US. Patent 2,867,- 981 issued January 13, 1959 to M. Berchtold, entitled Aero-Dynamic Wave Machine Functioning as a Compressor and Turbine; US. Patent 2,957,304 issued October 25, 1960 to M. Berchtold, entitled Acre-Dynamic Wave Machine Used as a Supercharger for Reciprocating Engines; U.S. Patent 2,959,344 issued November 8, 1960 to E. Niederrnan, entitled Reverse Cycle Aero- Dynamic Wave Machine; and US. Patent 2,970,745 issued February 7, 1961 to M. Berchtold, entitled Wave Machine. All of the aforementioned patents are assigned to the I-T-E Circuit Breaker Company.

In the construction of pressure exchangers, also known as aero-dynarnic wave machines, it is not always possible to have the rotor of the machine rotating at the r.p.m. necessary for optimum results. That is, in the event it is desirable to use the pressure exchanger as a supercharger, and to have the pressure exchanger directly or belt-driven from the reciprocating engine being supercharged, then there will be a variation in the speed of the rotor.

Unfortunately, the mis-timing of the waves within the machine are detrimental to low pressure scavenging as the rotor speed is reduced. Furthermore, there will be an undesirable back-flow from the pick-up or high pressure outlet port as a result of the mis-timing of the waves created by the slowing down of the rotor.

It is a primary object of our invention to provide a novel construction for a pressure exchanger whereby a variable speed rotor will have minimum effect on the mass flow out of both the high pressure outlet port and the low pressure outlet port.

Another object of our invention is :to provide a construction in which a pressure exchanger is provided with means located between the high pressure zone and the low pressure zone in the direction of rotation, which means will permit an elevation of pressure to thereby increase the mass flow in both the high pressure and low pressure outlet ports.

Still another object of our invention is to provide a construction whereby a pocket is located in the first or cold stator plate between the high pressure outlet port and the low pressure inlet port in the direction of rotation.

Another object of our invention is to provide a construction whereby a pocket is located in the first or cold stator plate between the high pressure outlet port and the 3,206,107 Patented Sept. 14, 1965 low pressure inlet port in the direction of rotation and a second pocket located between the high pressure inlet port and low pressure outlet port in the direction of rotation.

Another object of our invention is to provide a construction whereby a pocket is located in the first or cold stator plate between the high pressure outlet port and the low pressure inlet port in the direction of rotation whereby additional fluid and high pressure is introduced into the first pocket.

These and other objects of our invention will be apparent from the following description when taken in connection with the drawings in which:

FIGURE 1 is a cycle diagram showing the various conditions existing within the rotor of the pressure exchanger under optimum operating conditions, namely, when the rotor is rotated at design rpm.

FIGURE 2 is a cycle diagram of pressure exchanger similar to FIGURE 1 but illustrates the nus-timing of the waves within the rotor when the rotor is driven at a speed less than design speed.

FIGURE 3 is a partial cycle diagram illustrating a first pocket of our invention and the manner in which the pressure in the zone between the high and low pressure zones in the direction of rotation can be increased.

FIGURE 4 shows a cycle diagram of a pressure exchanger with the novel pocket arrangement of FIG- URE 3 but shows a modification whereby additional pressure can be introduced into the rotor through the additional pocket.

FIGURE 5 is a cycle diagram similar to FIGURE 3 but illustrates the manner in which a novel second pocket can be utilized in a pressure exchanger to increase the efliciency thereof.

In many applications, where a pressure exchanger is used as a supercharger for a reciprocating engine, the reciprocating engine will operate over a large speed range, as for example, from 500 to 2,500 rpm. In order to avoid the necessity of providing a separate prime mover for the pressure exchanger and also for the purposes of mechanical simplicity, it is desirable to drive the pressure exchanger directly from the reciprocating engine by way of a fixed ratio drive means from the crankshaft of the reciprocating engine. Thus, in such situations, the pressure exchanger will operate over the same general speed range as the reciprocating engine. The use of a pressure exchanger supercharger and reciprocating engine is illustrated and described in the aforementioned US. Patents 2,853,987 and 2,957,304.

In FIGURE 1 I have shown the wave diagram for a pressure exchanger in which the rotor is rotated with respect to the stator plates at design speed and, therefore, operating under optimum conditions. A more detailed description of the optimum operating conditions of a pressure exchanger is illustrated in the aforementioned US. Patents 2,867,981, 2,957,304, 2,959,344 and 2,970,745.

For the proper operation of a pressure exchanger as as supercharger for a reciprocating engine, it is desirable that no contaminated hot gases enter the pick-up or high pressure outlet port D. That is, the high pressure interface HPI should not reach into the high pressure outlet port D and, furthermore, the low pressure interface LPI should have left the rotor 30 before or at least at the closing of the low pressure outlet port A. That is, the high pressure interface created at the leading edge 5 of the high pressure inlet port C should terminate at the trailing edge 7 of the high pressure outlet port D and the low pressure interface created at the leading edge 2 of the low pressure inlet port B should terminate at the trailing edge 3 of the low pressure outlet port A.

In general, the pressure in the field I will be somewhat higher than in the field I. That is, the wave created at the leading edge 6 of the high pressure outlet port D will be a compression deceleration wave and identified by the numeral 66. Thus, if the wave 66 is a compression wave, the flow speed in the rotor will be reduced as shown by the change in the high pressure interface between I-IPI and I-IPI. That is, as the high pressure interface crosses the wave 66, the flow speed in the rotor will be reduced. The compression wave as will result in an increase or the pressure so that the field 1 will be greater than the field I which will also reduce the flow speed still further and, hence, will result in a reduction of the mass flow out of the high pressure outlet port D. On the other hand, if the Wave 66 is an expansion acceleration wave, the flow speed will be increased and, hence, the mass flow through the high pressure outlet port D will be increased.

The magnitude of the mass fiow moving through the high pressure outlet port D is a function of the demand of the reciprocating engine being supercharged by the pressure exchanger. Hence, the pressure in the field I depends on the flow demands of the reciprocating engine. The higher the demands of the reciprocating engine, the lower will be the pressure of the field I and the lower the demand of the reciprocating engine, the higher will be the pressure of the field I The portion of the rotor located between the high pressure inlet port C and the high pressure outlet port D indicated by the field I and I is generally referred to as the high pressure zone of the rotor 39. The low pressure zone III is in that portion of the rotor located between the low pressure inlet port B and the low pressure outlet port A. The higher the fiow speed in the field III, the earlier the interface LPI will reach the trailing edge 3 of the low pressure outlet port A.

It is essential to provide complete scavening of the machine through the low pressure outlet port A. That is, the low pressure interface must reach the right-hand end of the rotor 30 before the rotor 30 is closed by the trailing edge 3 or, ideally, exactly when the channels within the rotor 30 are closed by the trailing edge 3. If this sequence does not exist between the pressure exchanger, the contaminated gases exist in the field III will be trapped in the rtor and may subsequently be discharged through the high pressure outlet port D. Although this efiect is substantially minimized by the reverse cycle illustrated in FIGURE 1, it is nevertheless a condition to be avoided when possible.

In order to avoid incomplete low pressure scavenging, a predetermined minimum amount of flow speed in the field III is required. The flow speed in the low pressure zone III, depends on the pressure existing in the field II in the sense that the higher the pressure in the field II, the higher will be the fiow speed in the field III. However, the pressure in the field II depends on the pressure in the field I Thus, the higher the pressure in the field I the higher will be the pressure in field III and, therefore, the greater will be the flow speed to achieve complete scavenging through the exhaust or low pressure outlet port A.

It, therefore, becomes clear that the level of pressure in the field I determines the degree of low pressure scavenging through the low pressure outlet port A since the higher the pressure in the field I the earlier the low pressure interface LPI will reach the low pressure outlet port A. To put this another way, the higher the flow speed demands of the reciprocating engine being supplied with compressed air through the high pressure outlet port D, the lower will be the pressure in the field I thereby subsequently resulting in a reduction of the flow speed in the field III and possible incomplete low pressure scavenging.

In the illustration of FIGURE 1, there is shown basically the ideal cycle in which there is complete high pressure scavenging between the leading edge 6 and the trailing edge 7 of the high pressure outlet port D and complete low 4 pressure scavenging between the leading edge 1 and the trailing edge 3 of the low pressure outlet port A. i

In FIGURE 2, we have shown a wave or a cycle diagram for a pressure exchanger in which the rotor 30 is rotated at a speed below the design speed of FIGURE 1. In this case, there are two effects which simultaneously tend to jeopardize the low pressure scavenging to such an extent that contaminated hot gases may remain trapped in the rotor and subsequently leave through the high pressure outlet port D. This efiect is extremely undesirable since these contaminated hot gases would then be fed by the pressure exchanger directly to the reciprocating engine being supercharged thereby and could result in the stalling of the reciprocating engine.

As seen in FIGURE 2, a compression acceleration wave CA is created when the rotor 31 is opened by the leading edge 5 of the high pressure inlet port C. This Wave CA arrives too early at the hot stator plate 40, that is, before the high pressure outlet port D has been opened by its leading edge 6. The early arrival of the wave CA can be seen by comparison of FIGURES 1 and 2. Since the wave CA impinges upon the stator plate 40, it will be reflected in the closed channel ends as wave CA. The pressure behind the wave CA in the field I is considerably higher than the pressure in the field I. In fact, the pressure in the field I is higher than the pressure in the high pressure inlet port C and, hence, when the wave CA arrives at the high pressure inlet port C, there will be an out-flow of gas into the port C as shown by the arrow 50. The wave CA will be reflected at the port C and travel to the left through the rotor as wave CD.

When the high pressure outlet port D is opened by the leading edge 6, an expansion acceleration Wave EA will be created in the rotor so that the pressure in the field I will be reduced from the pressure existing in the field I to a magnitude approximately that pressure in the high pressure outlet port D. The pressure in the field I could be higher or lower than the pressure in the field I, the difierence being relatively small. The pressure in the field I, on the other hand, is significantly higher of the order of twice as high or more than the pressure in the field I. Therefore, the effect of mis-timing of the wave CA by virtue of too low a rotor speed is the existence of a high pressure hand identified by the field I traveling upstream in the rotor.

Upon the arrival of the wave EA at the high pressure inlet port C, the Wave will be reflected as wave EA thereby re-establishing in-fiow conditions from the high pressure inlet port C into the rotor as indicated by the arrow 51. The field 1 which is bounded by the waves CD and EA, will upon reaching the high pressure outlet port D, cause an undesirable fiow reversal. That is, there will be an in-fiow from the high pressure outlet port D into the rotor as indicated by the arrow 52. This undesirable in-flow into the channels of the rotor corresponds to the undesirable out-flow into the high pressure inlet port C indicated by the arrow 50. However, the arrival of the wave EA re-establishes the out-flow conditions into the high pressure outlet port D as indicated by the arrow 53.

Upon the closing of the high pressure inlet port C by the trailing edge 8 an expansion deceleration wave ED is created. Behind the wave ED, in the field II, the pressure will be substantially below the pressure existing in both the high pressure inlet port C and the high pressure outlet port D. Since the rotor is operating below design speed, the wave ED will arrive too early at the stator plate 40 as can be seen by a comparison of FIGURES 2 and 1. Hence, an additional in-flow will result at the high pressure outlet port D as illustrated by the arrow 54.

Thus, in summary, the mass flow at both the high pressure inlet port C and the high pressure outlet port D are reduced as a result of the flow reversal fields existing in the corresponding ports. It must be noted that there are two flow reversal fields 52 and 54 acting at the high pressure outlet port D and only one flow reversal field 50 acting at the high pressure inlet port C. Therefore, the tendency is for the flow at the high pressure outlet port D to be reduced more than the flow in the high pressure inlet port C. However, when the pressure exchanger is used as a supercharger for a reciprocating engine, both the input flow at the high pressure inlet port C and the outgoing flow at the high pressure outlet port D must be the same. However, this can only occur if the flow of speeds at the high pressure outlet port D is increased; that is, if the pressure in the field I is increased. However, as the speed of the rotor is reduced, the pressure in the field I is decreased which is detrimental to low pressure scavenging.

When the low pressure outlet port A is opened by the leading edge 1, as shown in FIGURE 2, an expansion acceleration wave EA is generated and will arrive at the left end of the rotor (stator 40) before the low pressure inlet port B is opened by the leading edge 2. This is best seen by a comparison of FIGURES 1 and 2. However, the wave EA drops the pressure in the field III to a value close to ambient pressure and the flow speed is still directed toward the low pressure outlet port A. However, upon the reflection of the Wave EA as wave ED on the closed end of the rotor, a pressure will be generated which is considerably below the pressure existing in the low pressure outlet port A illustrated by the field III.

When the low pressure inlet port B is opened by the leading edge 2, a compression acceleration wave CA will be generated which will essentially re-establish the conditions in field III. When the low pressure field III bounded by the waves ED and CA arrives at the low pressure outlet port A, a flow reversal will occur thereby resulting in a back flow into the rotor indicated by the arrow 55. As the band III travels back and forth through the rotor, it generates a back flow each time it arrives at an open port. This is illustrated by the arrow 56 in the low pressure inlet port B. This undesirable flow reversal hinders the scavenging of the hot gases out through the low pressure outlet port A and, therefore, is extremely detrimental to low pressure scavenging.

Accordingly, there are two effects which are detrimental to low pressure scavenging as the rotor speed is reduced, namely, a reduction of the pressure in the high pressure zone I due to more flow reversals in the high pressure outlet port D than in the high pressure inlet port C, and also back flow in the low pressure ports A and B due to the mis-timing of the wave EA.

As the rotor speed is reduced, the proper operation of the pressure exchanger completely breaks down and, in effect, there is no supercharging for the reciprocating engine. At this point, it is necessary to have the pressure exchanger by-passed by means of a by-pass valve and a butterfly valve which is governed by the pressure differences between the ports C and D. A detailed description of this construction is set forth in the aforementioned US. Patent 2,853,985. However, the by-pass arrangement has many drawbacks in addition to the mechanical complications and additional expenses that are involved. At very low speeds, the butterfly valve will always be closed. If full fuel flow is applied to the reciprocating engine under these conditions, the reciprocating engine will not receive enough air and may smoke severely. It is, therefore, extremely desirable to have a construction wherein the pressure exchanger can run at very low speeds, as characterized by a possible negative difference between the ports D and C, and will maintain proper low pressure scavenging. In this case, it will be possible to supercharge the recprocating engine at low speeds and avoid the aforementioned smoke difficulties.

Our present invention provides an arrangement whereby the low speed diificulties are overcome without resorting to the aforementioned by-pass construction.

Our invention includes the two constructions, the first of which may solve the problem up to a point for some installations and may be a complete solution for other installations. The second feature is used in conjunction with the first feature and together these features provide a complete solution to the problem.

The first feaure of our invention is provided to mitigate the harmful effects of the mis-timing of the wave EA shown in FIGURE 2 and consists of the recess or pocket 70 placed in the first or cold stator plate 40 in the area between the trailing edge 7 of port D and the leading edge 2 of port B as seen in FIGURE 3.

As previously mentioned, the harmful effects of mistiming results from the low pressure existing in the field III which causes flow reversal. It is also recalled that the pressure in the field II is higher than the pressure in the field I11 and III. A recess or pocket 70 arranged in the manner shown in the FIGURE 3 allows certain quantities of fluid to pass from the field II into the field III. As a consequence, the pressure in the field III will be higher than without the pocket 70. In fact, the pressure in the field III may possibly even be higher than the pressure in the field III. That is, the flow reversals can be substantially reduced or even completely eliminated and low pressure scavenging, thereby materially improved, or in fact complete low pressure scavenging can be achieved. Thus, the recess or pocket 70 in effect provides for the fluid flow from field II to the field III as indicated by the arrow 58 to raise the pressure in the field III and thereby reduce or eliminate back flow of conditions in the low pressure outlet port A.

It is noted that the average pressure in the pocket 70 must be high enough in order for the pressure in the field III not to be below a dangerous value. In fact, it can be shown experimentally and analytically that if the pressure in the pocket 7 0 falls below a certain minimum, low pressure scavenging ceases to be complete.

However, the pressure in the pocket 70 depends on two conditions; the first is that the pressure in the field H must be high enough. However, as previously noted, when the rotor speed is decreased, the pressure in the field II falls. Secondly, the pressure in the pocket 70 depends on the timing of the wave EA, the slower the rotor turns, the earlier the wave EA arrives at the cold stator 40 and the shorter the distance a and the longer the distance b. A short distance for the length a means that there will be a small volume flow into the pocket 70 from the field II. A long distance b means a large volume flow from the pocket 70 into the field III. Hence, the shorter the length a and the longer the length b, the lower is the pressure in the pocket 70. To re-phrase this, the slower the rotor turns, the lower will be the pressure in the pocket 70. Thus, both of these conditions result in a decrease of the pressure in the pocket 70 with a decrease in the rotor speed and there exists a rotor speed in which the pocket 70 by itself is inadequate as a low pressure scavenging aid. However, this situation can be improved if the pressure in the pocket 70 is artifically increased by supplying fluid from an outside duct as illustrated in FIGURE 4. The duct 80 supplies high pressure fluid in the direction of the arrow 60 to the pocket 70 and the supply of this high pressure fluid can be from any outside source. That is, the pressure in the high pressure fluid for the duct 80 can be supplied from the exhaust of the reciprocating engine being supercharged by the pressure exchanger or it is possible to feed the duct 80 with air or gas tapped off somewhere in the pressure exchanger itself where high pressure fiuid is available.

One example is shown in FIGURE 4 wherein the field I is used as a supply of high pressure fluid. As previously mentioned, at low rotor speeds the wave CA created at the leading edge 5 is completely reflected as wave CA at the closed channel end thereby resulting in a very high pressure field I. It would be possible to divert some of this high pressure air through the duct 80 into the pocket 70 to maintain the required minimum pocket pressure as illustrated in FIGURE 4. In this case, it would be necessary to provide a check valve 81 in the duct 80 in order to avoid back flow of fluid from the pocket 70 into the 7 field I at the operating points where the pressure of the pocket '70 is high.

Still another possiblity is to provide some hot gas from the exhaust manifold of the reciprocating engine into the pocket 70. This has the advantage that sufiicient pressure is always available in the exhaust manifold of the reciprocating engine. However, it is not always desirable to introduce contaminated exhaust gases at this point of the cycle and, furthermore, it is possible that the duct 80 may be clogged by carbon particles existing in the exhaust gases.

However, the use of the pressure from the exhaust manifold of the reciprocating engine can be made practical with an arrangement illustrated in FIGURE Wherein a second pocket 90 is located in the cold stator plate 41. The pocket 90 is located between the trailing edge 8 of high pressure inlet port C and leading edge 1 of port A. A portion of the pocket 90 extends up to the leading edge 8 thereby forming a gap having a width t between the cold stator plate 41 and the rotor 30. Thus, at the trailing edge 8, the high pressure inlet port C remains partially open and fluid is allowed to flow through the gap 1 and then into the rotor as indicated by the arrow 5h. This results in an elevator pressure band in the rotor as shown by the area 11'. The pressure in the area II is in between the pressure in the field I and II. The pressure in field II is governed by the geometry of the pocket 90 and can be chosen such that the pressure in the first pocket 74) will always be high enough to guarantee complete low pressure scavenging. The geometry of the pocket shown in FIGURE 5 is one possibility that it has been tried and has proved to be successful. However, it could, for instance, be possible to slightly enlarge the high pressure inlet port C or to employ another geometric configuration for the pocket 90 in the gap.

Thus, the novel arrangement of providing the second pocket 90 insures that there will be sufiicient pressure in the field II to permit the flow of fluid through the first pocket 70 to the field III as indicated by the arrow 58 of FIGURE 3.

In the foregoing, we have described our invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of our invention within the scope of the description herein are obvious. Accordingly, we prefer to be bound not by the specific disclosure herein but only by the appending claims.

We claim:

1. A pressure exchanger comprising a rotor for receiving and discharging fluids, said fluids being supplied to said rotor from a high pressure inlet port and a low pressure inlet port; fluid being extracted from said rotor from a high pressure outlet port and a low pressure outlet port; a first and second stator plate; said high pressure outlet port and said low pressure inlet port being located in said first stator plate on one side of said rotor; said high pressure inlet port and said low pressure outlet port being located in said second'stator plate on the other side of said rotor; said rotor being rotatable with respect to said first and second stator plates; said high pressure inlet and outlet ports defining a high pressure zone of said rotor; said low pressure inlet and outlet ports defining a low pressure Zone of said rotor; means located between said high pressure and low pressure zone in the direction of rotation of said rotor to increase the pressure in said rotor between said zones; said means being located in said first stator plate, a duct means; said means being operatively connected by said duct means to a source of high pressure fluid, said duct means extending between said means and the source of high pressure fluid, a check valve located in said duct means to prevent flow of fluid from said means to said source of high pressure fluid.

2. A pressure exchanger comprising a rotor for receiving and discharging fluids, said fluids being supplied to said rotor from a high pressure inlet port and a low pressure inlet port; fluid being extracted from said rotor from a high pressure outlet port and a low pressure outlet port; a first and second stator plate; said high pressure outlet port and said low pressure inlet port being located in said first stator plate on one side of said rotor; said high pressure inlet port and said low pressure outlet port being located in said second stator plate on the other side of said rotor; said rotor being rotatable with respect to said first and second stator plates; said high pressure inlet and outlet ports defining a high pressure zone of said rotor; said low pressure inlet and outlet ports defining a low pressure zone of said rotor; means located between said high pressure and low pressure zone in the direction of rotation of said rotor to increase the pressure in said rotor between said zones; said means being located in said first stator plate; a duct means; said means being operatively connected by said duct means to said rotor in the area located between said low pressure inlet port and said high pressure outlet port in the direction of rotation of said rotor, and a check valve located in said duct means.

References Cited by the Examiner UNITED STATES PATENTS 2,852,915 9/58 Jendrassik 23069 X 2,904,244 9/59 Pearson 23069 3,012,708 12/61 Berchtold et al 23069 FOREIGN PATENTS 803,660 10/58 Great Britain.

LAURENCE V. EFNER, Primary Examiner.

WARREN E. COLEMAN, Examiner. 

1. A PRESSURE EXCHANGER COMPRISING A ROTOR FOR RECEIVING AND DISCHARGING FLUIDS, SAID FLUIDS BEING SUPPLIED TO SAID ROTOR FROM A HIGH PRESSURE INLET PORT AND A LOW PRESSURE INLET PORT; FLUID BEING EXTRACTED FROM SAID ROTOR FROM A HIGH PRESSURE OUTLET PORT AND A LOW PRESSURE OUTLET PORT; A FIRST AND SECOND STATOR PLATE; SAID HIGH PRESSURE OUTLET PORT AND SAID LOW PRESSURE INLET PORT BEING LOCATED IN SAID FIRST STATOR PLATE ON ONE SIDE OF SAID ROTOR; SAID HIGH PRESSURE INLET PORT AND SAID LOW PRESSURE OUTLET PORT BEING LOCATED IN SAID SECOND STATOR PLATE ON THE OTHER SIDE OF SAID ROTOR; SAID ROTOR BEING ROTATABLE WITH RESPECT TO SAID FIRST AND SECOND STATOR PLATES; SAID HIGH PRESSURE INLET AND OUTLET PORTS DEFINING A HIGH PRESSURE ZONE OF SAID ROTOR; SAID LOW PRESSURE INLET AND OUTLET PORTS DEFINING A LOW PRESSURE ZONE OF SAID ROTOR; MEANS LOCATED BETWEEN SAID HIGH PRESSURE AND LOW PRESSURE ZONE IN THE DIRDCTION OF ROTATION OF SAID ROTOR TO INCREASE THE PRESSURE IN SAID ROTOR BETWEEN SAID ZONES; SAID MEANS BEING LOCATED IN SAID FIRST STATOR PLATE, A DUCT MEANS; SAID MEANS BEING OPERATIVELY CONNECTED BY SAID DUCT MEANS EXTENDING BETWEEN SAID MEANS SURE FLUID, SAID DUCT MEANS EXTENDING BETWEEN SAID MEANS AND THE SOURCE OF HIGH PRESSURE FLUID, A CHECK VALVE LOCATED IN SAID DUCT MEANS TO PREVENT FLOW OF FLUID FROM SAID MEANS TO SAID SOURCE OF HIGH PRESSURE FLUID. 